Cathode ray tube



Filed Nov. 5, 1934 3 Sheets-Sheet l INVENTOR. (lllen B. DuMonr ATTORNEYS July 20, 1937. A, a DU NT 2,087,280

CATHODE RAY TUBE Filed Nov. 5, 1954 3 Sheets-Sheet 2 INVENTOR.

(l llen B.DuMont ATTORNEYS JuIy ZO, 1937. A. B. DU MONT CATHODE RAY TUBE s Sheets-Sheeb 3 Filed NOV. 5, 1934 INVENTOR. amen. B. DuN

ATTORNEYS Patented J My 20, 1937 UNITED STATES PATENT OFFICE CATHODE RAY TUBE Application November 6 Claims.

This invention relates to an improvement in the mechanical design and electrical characteristics of cathode ray tubes.

The object of the invention is to produce a 5 cathode ray tube which is extremely rugged mechanically, very sensitive, may be accurately lined up before sealing in, may be used at high voltages and high frequencies, and is cheaper to manufacture than tubes now being made.

The tubes now avaliable may be classified into two general types, 1. e. those in which the electrode generating, focusing and accelerating electrodes, as well as the deflecting electrodes, are mounted on a single stem; and those in which 15 the deflecting electrodes are not mounted on the common stem but are sealed in separately to the neck of the bulb. The first type has the advantage that it is relatively easy to line up all of the elements before the mount is sealed in, but has 20 the disadvantage that when high voltages are to be used it is impossible to get good spacing of the leads in the press because of the large number of leads required. The second type has the advantage that because of fewer leads through 25 the press suflicient insulation may be obtained for high voltage work, but it is more costly to build and the entire assembly cannot be lined up before scaling in. Both types are very fragile.

My new type of cathode ray tube, as disclosed 30 herein, overcomes all of the disadvantages of both types mentioned above and at the same time retains all of the advantages of both types. This construction consists of an inner well having a press on which the electron generating and fcusing electrodes are mounted, and a rim surrounding the press on which the deflecting and accelerating electrodes are mounted. As the leads to the electrodes in my improved tube are very short the need for lava or mica spacers is 40 obviated and yet the tube is much more rugged than the present types. In fact in several tests of my new tube the glass itself was broken before the elements were displaced. The tubes now available cannot withstand any such shocks in 45 spite of the spacers used.

In one form of my new construction all the low voltage leads are taken from the tube through the inner well and the high voltage leads from the rim so that it is possible to use very high 50 voltages without danger of breaking down. In a modification shown the leads are all taken from the tube through the rim, and the spacing is such that the danger is also eliminated in this type.

Another great advantage of my construction 55 is in the improved sensitivity. As my electrodes 5, 1934, Serial No. 751,499

are all compactly mounted near the base of the tube the distance between the screen and the deflection plates is large compared with the length of the bulb. With my construction I obtain an increased sensitivity of from 20 to 100 percent, depending on the type of tube of the prior art with which my new tube is compared.

In the drawings Figs. 1 to 8 show one type of tube construction in accordance with my invention; and Figs. 9 ton show a modification. i

Fig. 1 is a view partly in section, of the press of my new tube and the electrodes mounted thereon;

Fig. 2 is a view, partly in section, of the rim and adjacent portions of the bulb of my new tube with the electrodes mounted thereon;

Fig. 3 is a view, partly in section, showing the assembly of Figs. 1 and 2 with a tube and base to constitute a complete embo iment of my invention;

Fig. 41s a section along the lines 44 of Fig. 3;

Fig. 5 is a section along the lines 55 of Fig. 3;

Fig. 6 is a section along the lines 6-6 of Fig. 3;

Fig. 7 is a section along the lines l--l of Fig. 3;

Fig. 8 is a bottom plan view of my new tube with a base mounted thereon;

Fig. 9 is a view, partly in section, of a modification of my invention;

Fig. 10 is a section along the lines Ill-i0 of Fig. 9; and

Fig. 11 is a section along the lines l|-ll of Fig. 9.

Similar reference numerals refer to similar parts throughout the drawings.

In Fig. 1 a stem l2 terminates in a press l3 through which project leads l4, l5, l6 and I1. Secured to leads l5 and IS in a suitable manner is a filament l8 which terminates in an electron emitting ball l9 secured to the center of the filament. The filament is mounted within an insulator 20 having two similar elongated passages therethrough, as indicated by the dotted lines, through which the filament passes. The insulator 20 is spaced from a focusing electrode 22 by insulating spacers 23 which hold it in position.

Lead H is connected to and supports focusing electrode 22. Lead 14 is connected to and supports accelerating electrode 52. The structure shown in Fig. 1 is assembled, as shown in that figure, as the first step in manufacturing my tube. When mynew construction is used in gas tubes the electrode 52 may be omitted, if desired.

When the structure of Fig. 1 is completed the bottom of the stem 43 is sealed to the cylinder 42 of Fig. 3, as shown in Fig. 3.

In Fig. 2 a portion of the glass bulb 24 terminates in a rim 25 which, as may be seen from other figures, particularly Fig. 5, is annular. Projecting through this rim 25 are metallic rods 26, 21, 28, 23 and 30 to which are attached, respectively, leads 3|, 32, 33, 34 and 35. Secured to metallic rod 26 in any suitable fashion, as by welding, is another metallic rod 36 to which is attached an accelerating electrode 31. Secured to metallic rods 28 and 30 are a bottom pair of deflecting electrodes 38 and 33. Secured to metallic rods 21 and 29 are an upper pair of defiectingelectrodes 40 and M. It will be noted that the glass bulb 24 rises on the outside of the rim 25 and then falls to produce an inner, hollow cylinder 42.

As the structure of Fig. 2 is assembled the electrodes, which it will be noted are all readily accessible, are lined up so that the tube will operate properly when completed. In manufacturing cathode ray tubes in accordance with the prior art a large number of failures result due to the tubes notbeing properly lined up after they are sealed into the bulb. With my-construction failures due to this cause are completely eliminated and hence the cost "of manufacturing tubes by my process is greatly reduced due to this factor alone.

Having lined up the electrodes properly, the next step is to complete the tube. This is done by inserting the combined structure of Figs. 1 and 2 into the bottom of a hollow cathode ray tube 44. A flange at the base of the glass portion 24 is then sealed to the tube 44 completing the structure of the tube proper. The

' stem l2 has therein a-tub'ulation 6| through which the bulb is evacuated and sealed ofl. A base 45 is then secured to the bottom of the tube and the manufacture is complete.

The base is provided with six plugs, which fit into a standard cathode ray tube socket, and with three binding posts to which various leads are connected. For convenience in following the description, the plugs and binding posts have been given the same numerals as are used for the leads to which they are connected, suflixed in each case by the letter A, as shown particularly in Fig. 8. It will be noted that the inner cylindrical portion of the bulb "42 new forms an inner well within the cathode ray tube in which the press I3 is mounted and this well terminates in the inner annular rim 25. The low voltage leads are all taken through the press I 3, while the high voltage leads are all taken through the rim 25, affording a. degree of spacing between the leads which permits the use of extremely high voltages without any danger whatever.

In Figs. 9 to 11, I have shown a modification of my 'tube. In this modification all of the leads are taken from the tube through the rim 25, but some of the electrodes are mounted within the inner well as before. To the four low voltage leads are secured rods 41, 48, 43 and 50 which support a glass bead 5! which is mounted within the inner well of the tube. To these rods 41 to 50 are then secured the filament l3, the focussing electrode 22,, and the accelerating electrode 52. It will be noted that in the construct ion shown in Figs. 9 to 11 the glass bead 5| is substituted for the press l3. In constructing the modification shown in these figures the glass bead and the rods projecting therethroush are first assembled. The electrodes are then secured to these rods; the rods are secured to leads l4 to H; the accelerating and deflecting electrodes are secured to rods 28 to 30; the bulb of the tube proper is sealed to the flange 45; the tube is evac- 5 uated as in the previous construction; and the base is supplied as before.

What is claimed is:

1. A cathode ray tube comprising an inner well, a press within said inner well, a plurality of electrodes mounted on said press within said well, a plurality of leads from said electrodes passing through said press, a rim surrounding said inner well, a plurality of electrodes mounted on said rim, and a plurality of leads from said electrodes passing through said rim.

2. A cathode ray tube comprising an envelope having an inner well terminating in an inner rim, a press within said well, a plurality of metallic rods through said press, a filament secured to two of said metallic rods, 9. fooussing electrode secured to a third of said metallic rods, an accelerating electrode secured to another of said metallic rods, a plurality of metallic rods mounted in said rim, an accelerating electrode 2 securedto'one of said metallic rods and two pairs of deflecting plates secured to the other of said metallic rods.

3. A cathode ray tube comprising an envelope having therein an inner well terminating in an 3 inner rim, a press within said well, a plurality of metallic rods mounted in said press, a filamentconnected to one of said metallic rods, a focussing electrode connected to another of said metallic rods, a plurality of metallic rods mounted 3 in said rim, an accelerating electrode connected to one of said metallic rods, and a plurality of deflecting electrodes connected to the other of said metallic rods.

4. A cathode ray tube comprising'an envelope 40 within said well, a plurality of metallic rods 45 passing through said head for supporting the balance of said electrodes, and means for connecting said rods which pass through the glass bead to those of the rods which pass through the rim which do not support the first set of electrodes mentioned.

5. A cathode ray tube device comprising an envelope having an inner well, an inner rim surrounding said well, a plurality of electrodes within said device, a press within said well, a plurality of leads mounted within said press and supporting some of said electrodes within said well, and a plurality of leads mounted in said rim and supporting the balance of said electrodes above said rim.

6. A cathode ray tube comprising an envelope having an inner well and an inner rim, a press within said well, means for supporting a plurality of electrodes from said press within said well. leads for said electrodes passing through said press, means for supporting a plurality of electrodes from said rim above and in line with the electrodes supported from said press, and leads from the electrodes mounted on said rim passing through said rim.

ALLEN B. DU MONT. 

